QantasLink 717-200 VH-YQU was forced to turn back to HBA about 20 minutes into its flight QF1506 to MEL this afternoon. The flight eventually departed for the 2nd time at 7.54pm. This has resulted in Qantas 737-800 VH-XZJ operating a special QF1013 MEL-HBA flight tonight (just about to touch down) in place of the normal QantasLink QF1507 flight.